1. Field of the Invention
The present invention relates to heat exchangers and, more particularly, to a surface for entwining one fluid flow about another fluid flow.
2. Description of the Prior Art
Heat exchangers for exchanging heat between two adjacent flows of fluid are well known. Embodiments of these heat exchanger include the use of a pair of concentric pipes wherein one fluid flows in the central pipe while a second fluid flows in the space defined between the central and an outer pipe. The direction of flow of the fluids may be the same or counter to one another. Various structures have been employed to direct the segregated fluids into and out of such heat exchangers. Another well known heat exchanger is a device having a first pipe for conveying a first fluid into, through and out of a container having a second fluid therein. In a variant heat exchanger, fins may be attached to a conduit for a first fluid to maximize the surface area of contact with a second fluid to promote an exchange of heat therebetween. In yet a further type of heat exchanger, a plurality of pipes convey in parallel a first fluid through a container for a second fluid; a first plenum is disposed in fluid communication with one end of the plurality of pipes to direct fluid thereinto and a second plenum is disposed at the second end of the plurality of pipes to collect fluid therefrom.
Generally, the junction itself at which the flows of two fluids of a heat exchanger is not capable of performing an effective or efficient exchange of heat. That is, these junctions are primarily intended for purposes of channeling the fluid flows and are not designed deliberately to perform a heat exchanging function.
Heat exchangers having one fluid flow enveloped by a second fluid flow maintain such relationship of the fluids throughout the flow within the heat exchanger. Few, if any, heat exchangers of this type are capable of alternately enveloping one fluid with the other fluid during the flow through the heat exchanger.